Fusarium Wilt
Fusarium WiltFusarium Wilt
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Fusarium udum Butler
Symptoms:
• The leaves of the affected plants become yellowish in color, then drop and finally the whole plant dry out.
• These types of symptoms can be easily confused with shortage of moisture in the soil though there is plenty of moisture in the soil where these symptoms develop.
• The disease in fact can be diagnosed by seeing the black streaks on the wood after removing the outer epidermal strip from the major roots.
Control Measures
• It is difficult to control the disease due to the soil borne nature of the causal fungus.
• However, its incidents can be reduced considerably by taking certain precautions. Thses include following a three to four year crop rotation, taking a mixed crop of jowar and arhar and collecting and burning the plant trasnes left after harvesting.
• Best control is to plant disease resistant varieties like Amar, Azad, Asha (IPCL-87119), Maruthi, C-11, BDN-1, BDN-2, NP-5 etc.
CankerCanker
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Causal Organism:
Rhizoctonia bataticola (Taub.) Butler
Macrophomina phaseolina (Tassi) Goidanich
Symptoms:
• Infected plants suddenly and prematurely dry up. When such plants are uprooted their roots are rotten and shredded.
• The finer roots are mainly affected and have dark, blackend streaks underneath their bark with evident dark sclerotial bodies.
• Such roots are brittle and break when touched. Under hot, humid conditions root rotting extends to the base of the stem.
• Early symptoms on stems and branches are spindle-shaped lesions with light gray centers and brown margins with scattered pycnidial bodies.
• The lesions coalesce and cause the branches or whole plants to dry up and die.
Control Measures:
• In case of severe intensity of this disease, the crop should be sprayed with Mancozeb 75 WP at the rate of 2.5 kg per hectare.
• A suitable crop rotation should be followed if the cankers are a problem in the same field every year.
Bacterial Leaf SpotBacterial Leaf Spot
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Causal Organism:
Xanthomonas campestris pv. cajani
(Kulkarni, Patel & Abhyankar) Dye
Symptoms:
• In India the disease usually appears in the rainy season during July and August.
• It can be seen on the lower leaves of plants that are about 1 month old as small necrotic spots surrounded by bright yellow halos.
• Later, rough, raised, cankerous lesions appear on the stem. Leaf spots do not usually cause defoliation.
• Cankers can cause stems to break, but the broken part usually remains attached to the plant. Stems often break at the point where the primary leaves are attached.
• Often, the affected plants do not break, and the stem cankers increase in size until they are 15-25 cm long.
• In cases of severe infection the affected branches dry.
Control:
• Use resistant varieties.
• Select well drained fields.
• Always selects seeds from healthy crops.
• Spray antibiotics like streptocycline and 250 ppm i.e. 2.5 g/10 lit of water.
Cercospora Leaf SpotCercospora Leaf Spot
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Causal Organism:
Cercospora cajani Hennings (most prevalent)
Cercospora indica Singh
Cercospora instabilis Rangel
Cercospora thirumalacharii Sharma & Mishra
(Teleomorph: Mycovellosiella cajani [Henn.]
Rangel ex Trotter)
Symptoms:
• First appear as small circular to irregular necrotic spots or lesions usually on older leaves.
• These lesions coalesce causing leaf blight and defoliation.
• During epidemics lesions appear on young branches and cause their tips to dry and die back.
• The Indian isolates of the pathogen produce a fluffy mycelial growth on their lesions, while the African isolates produce concentric zonations on their lesions.
Control
• Use resistant varieties.
• Select field away from perennial pigeon peas which are a source of inoculum.
• Always select seeds from healthy plants.
• Spray maneb @ 3g/litre of water or carbendazim 1 g/litre.
Sterility MosaicSterility Mosaic
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Causal organism:
Mycoplasma
Vector:
Eriophyid mite Aceria cajani Channabasavanna
Symptoms:
• The affected plants become light greenish in color which can be easily differentiated from dark green healthy plants.
• Leaves are reduced in size. Affected plants remain stunted and branch profusely, as a result of which they appear bushy.
• No flowers and fruits are borne on such affected plants resulting in total loss of yield. Sometimes only a few branches in the plant are affected others remaining healthy.
• In such cases the yield reductions are patial. The virus is not seed borne.
Control Measures
• Plant resistant varieties like Pusa-885, Asha, Sharad (DA-11), Narendra-Arhar-1, Bahar etc.
• Control mites by spraying 0.1% Oxydemton methyl (Metasystox). Start spraying as soon as first affected plants are seen in the field. Three to four sprays are needed to control the mites.
Powdery MildewPowdery Mildew
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Causal organism:
Oidiopsis taurica (Lev.) Salmon
(Teleomorph: Leveillula taurica [Lev.] Amaud)
Symptoms
• Infected plants have white powdery fungal growths on all their aerial parts, especially the leaves, flowers, and pods.
• Severe infections result in heavy defoliation.
• The disease causes stunting of young plants, followed by the visible symptoms of white powdery growth that appear gradually before the flowering stage.
• The initial symptoms develop as small chlorotic spots on the upper surface of individual leaves and subsequently the corresponding lower surfaces develop white powdery patches.
• When the fungus sporulates, this white powdery growth covers the entire lower leaf surface.
Control
• Use resistant varieties.
• Select fileds away from perennial pigeon pea which are a source of inoculum.Sow late (after July) in India, to reduce disease incidence.
• Spray wettable sulphur @ 1g/litre.
OR
• Triademefori 25 @ 0.03%.
OR
• Carbendazim 0.5 g-1.0 g/lit
